Electric bicycle drive unit fixing structure

Abstract

An electric bicycle drive unit fixing structure (50) by which an electric mid-motor drive unit (30) is floatingly attached to a drive receptacle (21) of a bicycle frame (20), wherein the drive receptacle (21) comprises two mutually parallel, vertically and to the frame fixed frame flanges (211, 212), wherein the drive unit housing (34) comprises two parallel and vertical housing flanges (41, 42), wherein one housing flange (41) is attached to one frame flange (211) and the other housing flange (42) is attached to the other frame flange (212), defining flange pairs, respectively, and wherein the two flange pairs each comprise at least one rubber mount (80) by which the frame flanges (211, 212) are connected to the associated housing flanges (41, 42) in a floating and rubber-elastic manner, so that the housing flanges (41, 42) in each case do not directly abut against the corresponding frame flanges (211, 212), but are spaced apart from the corresponding frame flanges (211, 212) by a spacing gap (58) having a gap size X of at least 0.3 mm.

Description

Technical Field

[0001] This invention relates to a fixing structure for an electric bicycle drive unit, used to connect a mid-mounted motor drive unit to the bicycle frame of an electric bicycle. Background Technology

[0002] As used herein, an electric bicycle is understood to be any type of bicycle including an auxiliary electric drive unit that provides corresponding electric motor drive power to increase the human drive power input by the rider to the pedal crank when needed. This invention relates to a mounting structure for a so-called mid-drive motor unit that both rotatably supports the pedal crankshaft and includes an output element, such as at least one sprocket, that drives the rear wheel of the electric bicycle. In a mid-drive motor unit, high mechanical forces can be applied to the drive unit for short periods, and these forces must be transmitted to the bicycle frame via a mounting structure.

[0003] A mounting structure is known from DE 102016112778A1 and DE 102017201617A1, in which the bicycle frame includes two parallel vertical frame flanges, and the corresponding vertical housing flange of the drive unit housing is fixed to these vertical frame flanges. While this mounting structure offers high mechanical stability, structural noise from the drive unit housing can be transmitted to the bicycle frame. However, the acoustic characteristics of the e-bike drive unit are increasingly becoming a key concern for end-consumer purchasing decisions. Summary of the Invention

[0004] In view of this background, the object of the present invention is to provide a powerful electric bicycle drive unit fixing structure with improved acoustic properties.

[0005] With the electric bicycle drive unit fixing structure according to the invention, the electric mid-drive motor drive unit is attached to the drive housing of the bicycle frame in a floating manner, thus completely avoiding a rigid connection between the drive unit housing and the bicycle frame. The bicycle frame drive housing includes two parallel and substantially perpendicular frame flanges fixed to the frame. The drive unit housing includes two parallel and substantially perpendicular housing flanges, which are respectively located at the distal or proximal end when the drive unit is installed, but preferably at the proximal end, i.e., inside the frame flanges. The left housing flange is attached to the left frame flange, and the right housing flange is attached to the right frame flange. The drive unit is thus attached to the bicycle frame via two flange pairs, wherein each flange pair includes a frame flange and an associated housing flange. The frame flanges and / or housing flanges need not be defined by rods vertically erected in a vertical plane. In particular, the housing flanges may also be defined by a flange surface of the housing body that does not project vertically from the embedded portion of the drive housing.

[0006] Each of the two flange pairs includes at least one rubber support, through which the frame flange is connected to the associated housing flange in a floating and rubber-elastic manner, such that the two housing flanges do not directly abut against the corresponding frame flange. A gap of at least 0.3 mm is defined between each housing flange and the frame flange. The rubber support in this case does not necessarily have to be made of rubber, but rather provides a non-rigid, elastically connected rubber-elastic support, which reduces the transmission of structural noise to some extent compared to a rigid connection.

[0007] Even with greater pedaling and driving forces, this ensures that no direct mechanical contact is established between the metal drive housing and the metal bicycle frame. This prevents structurally transmitted noise from the drive housing to the bicycle frame. Therefore, this significantly reduces structurally transmitted noise emissions overall, resulting in a substantial improvement in the acoustic characteristics of the e-bike.

[0008] Preferably, the rubber support comprises a substantially annular or cylindrical rubber sleeve through which the pedaling and driving forces acting on the drive unit are transmitted substantially radially. Sufficient dimensions of the rubber sleeve can be easily achieved by appropriately designing its length, diameter, and radial material thickness. This allows even very large forces to be transmitted without significant movement of the drive unit relative to the bicycle frame. In particular, this method reliably ensures that the housing flange does not contact the corresponding frame flange.

[0009] Preferably, the rubber sleeve is disposed in a substantially cylindrical annular gap between the rigid outer sleeve and the rigid inner sleeve. The combination of the rigid outer sleeve, rubber sleeve, and rigid inner sleeve can be provided as a prefabricated component, wherein the outer circumferential surface of the rubber sleeve is connected to the inner circumferential surface of the outer sleeve, and its inner circumferential surface is connected to the outer circumferential surface of the inner sleeve, preferably by material bonding, for example by vulcanization. Alternatively and more preferably, a shape-locking connection between the respective interface pairs can also be provided. The outer sleeve and / or inner sleeve are preferably made of metal.

[0010] Preferably, the outer sleeve of the sleeve assembly is disposed in a through hole in the housing flange. In this way, the sleeve assembly can be inserted into the corresponding through hole in the housing flange from the proximal direction, i.e., from the center of the drive unit to the distal side, so that it can be attached to the corresponding distal frame flange by a corresponding fastening device, such as a bolt.

[0011] Preferably, the inner sleeve is directly attached to the associated frame flange by force locking and / or form locking. For example, the inner sleeve may include an internal thread into which the external thread of a bolt inserted into a corresponding bolt opening of the frame flange from the distal direction is screwed. In this way, the drive unit can be secured to the bicycle frame by screwing only one bolt (e.g., a threaded screw) into the inner sleeve from the distal direction at each of the two flange pairs.

[0012] Preferably, the rubber sleeve includes a retaining ring at its longitudinal distal end, which is axially positioned between the outer sleeve and the corresponding frame flange. Relative to the left and right flange pairs, the retaining ring ensures a constant minimum clearance between the frame flange and the corresponding housing flange. This ensures that even under heavy mechanical loads, direct contact will not occur between the frame flange and the associated housing flange, even at certain points or for a very short period of time.

[0013] Preferably, a shape-locking structure is provided on the inner side of the outer sleeve and the outer side of the inner sleeve, which locks with a complementary shape-locking structure on the outer and inner sides of the rubber sleeve. Therefore, the rubber sleeve is effectively engaged with the inner and outer sleeves in a non-rotatable manner by the forced locking structure. This is particularly important when the sleeve assembly is secured to the frame flange and / or housing flange via a threaded connection, through which torque is applied to the sleeve assembly during assembly.

[0014] Preferably, the outer sleeve includes an anti-rotation structure at its proximal longitudinal end, by which the outer sleeve is supported at the drive unit housing in a torque-resistant manner. The anti-rotation structure is particularly necessary when the corresponding inner sleeve of the sleeve assembly is secured to the frame flange by bolts or screws. This anti-rotation structure prevents the sleeve assembly from rotating during assembly along with the movement of the screws. Attached Figure Description

[0015] In the following description, embodiments of the invention will be explained in more detail with reference to the accompanying drawings. In the drawings:

[0016] Figure 1 The vertical section II of the electric bicycle drive unit mounting structure is shown, in which the centrally mounted motor drive unit is mounted on the side drive housing of the bicycle frame.

[0017] Figure 2 It shows Figure 1 The horizontal section II-II of the fixed structure of the electric bicycle drive unit,

[0018] Figure 3 It shows including Figure 2 An enlarged view of the left-hand side fixing structure III of the three-part assembly, and

[0019] Figure 4 It shows Figure 3 A set of outerwear and innerwear. Detailed Implementation

[0020] Figure 1 A schematic vertical cross-section of an electric bicycle 10 with a bicycle frame 20 and a mid-mounted motor drive unit 30 is shown. In this case, the drive unit 30 is designed to be purely auxiliary and to support the rider's human driving force during riding.

[0021] In the present case, only a small portion of the downtube and drive housing 21 of the electric bicycle 10 is shown. The drive unit 30 includes a closed drive unit housing 34, in which an electric drive motor 32 and a gearbox 31 are housed. The gearbox 31 may have a fixed gear ratio and may be a shift gearbox or a continuously variable transmission (CVT). Furthermore, a lateral output shaft 35 is carried within the drive unit housing 34, which in this case also constitutes the bottom bracket support shaft. Typically, the output shaft and the bottom bracket support shaft can be arranged separately from each other, for example, concentrically. Left and right pedal cranks 36 are located at the two longitudinal ends of the output shaft 35, and pedals 37 are located at their respective ends. An output element 38, configured as a gear with more than 20 teeth, is rotatably fixed at the output shaft 35, driving the rear sprocket of the bicycle 10's rear wheel via a chain drive.

[0022] Figures 1 to 3 Two fixed structures 50 are shown, through which the drive unit 30 is buoyantly attached to the drive housing 21 of the bicycle frame 20. The drive housing 21 includes two frame flanges 211 and 212, which are fixed to the frame and parallel to each other, and are respectively arranged in a vertical plane, thereby defining a clamp-like housing with an opening at the bottom and a U-shaped cross-section. Parallel housing flanges 41 and 42 of the drive housing 34, also arranged in the vertical plane, are attached to the two frame flanges 211 and 212 and project vertically upward from the enclosed drive housing 34. Typically, the housing flanges may alternatively be integrated into the actual drive housing 34.

[0023] The left frame flange 211 is elastically mounted to the left housing flange 41 via rubber supports 80, and the right frame flange 212 is elastically mounted to the right housing flange 42 via the same rubber supports 80. Both housing flanges 41 and 42 include cylindrical through-holes 49 into which a sleeve assembly 60 is inserted proximally. The sleeve assembly 60 substantially comprises a rigid outer sleeve 90 defined by a metal sleeve body 92, a rigid inner sleeve 70 defined by a metal sleeve body 72, and a substantially cylindrical elastic rubber sleeve 82 defining the rubber supports 80. The rubber sleeve 82 fills the cylindrical annular gap 100 between the substantially cylindrical inner circumferential surface of the outer sleeve 90 and the substantially cylindrical outer circumferential surface of the inner sleeve 70. The rubber sleeve 82 is bonded or vulcanized to the outer sleeve 90 and the inner sleeve 70, respectively.

[0024] The outer body of the outer jacket is constructed into a generally cylindrical shape at its outer circumferential surface 99, and is inserted into the cylindrical inner circumferential surface of the through hole 49 by clamping its outer circumferential surface 99.

[0025] Figure 4 The sleeve assembly 60 without the rubber sleeve 82 is shown. Especially... Figure 4 As can be clearly seen, the outer sleeve 90 includes a stop ring flange 94 standing in a radial plane on the outer side of its proximal longitudinal end. This stop ring flange 94 includes an anti-rotation structure 98 achieved by two chordally flattened portions 98', whose chords are parallel to each other. The outer sleeve 90, and thus the complete sleeve assembly 60, is rotatably locked in the pre-assembled state and in the final assembled state at the drive unit 30 because the flattened portions 98' cooperate with the corresponding flat opposing surfaces 34' of the drive unit housing 34 to establish a rotational shape lock, as shown in... Figure 1 It can be seen in the image.

[0026] On the inner side of the outer sleeve 92, three shape-locking recesses 96 are provided at each of the two longitudinal ends of the sleeve 92. These three shape-locking recesses correspond rotatably to similar shape-locking ribs 74 on the outer side of the inner sleeve 72. A total of six shape-locking recesses 96 and a total of six shape-locking ribs 74 engage with the corresponding complementary shape-locking ribs and recesses of the rubber sleeve 82 in a shape-locking manner, thus ensuring a reliable rotationally fixed connection between the inner sleeve 70 and the outer sleeve 90 even under high torque during assembly.

[0027] The inner sleeve 70 includes an internal thread 76 on its inner side, into which the external thread 56 of the bolt 52 is screwed from its proximal end. The bolt 52 includes a cylindrical threaded shank 54 and a bolt head 56. The associated frame flanges 211, 212 include stepped through-holes 27 through which the bolt 52 is inserted during assembly and screwed into the inner sleeve thread 76 along with its threaded shank 54, which includes the external thread 56. Thus, the inner sleeve 70 is frictionally attached to the frame flanges 211, 212.

[0028] Especially Figure 3 As can be seen, the rubber sleeve 82 includes a limiting ring 88 projecting radially outward in a radial plane at its distal longitudinal end. This limiting ring, in the assembled state, fills only the axial gap 58 between the distal end face 43 of the outer sleeve 90 and the proximal flange face 23 of the associated frame flanges 211, 212 in the region of the outer sleeve 90. Therefore, in the stationary state, the limiting ring 88 ensures that the gap x between the housing flanges 41, 42 and the associated corresponding frame flanges 211, 212 is approximately 1.0 mm. Because at least one fixing structure 50 is provided on both the left and right sides, the drive unit 30 is thus centered in a floating manner between the two frame flanges 211, 212.

[0029] In dynamic conditions, i.e. during operation, this always ensures a minimum clearance that is always large enough that the housing flanges 41, 42 do not contact the associated frame flanges 211, 212. This prevents structurally propagated noise from the drive unit housing 34 to the bicycle frame 20, resulting in an overall reduction in noise emissions from the drive unit 30 compared to a fixed structure with a rigid connection from the drive unit to the bicycle frame.

Claims

1. An electric bicycle drive unit fixing structure (50), wherein an electric mid-mounted motor drive unit (30) is floatingly attached to a drive housing (21) of a bicycle frame (20) via the electric bicycle drive unit fixing structure. in, The drive housing (21) includes two parallel and vertical frame flanges (211, 212) fixed to the frame. The drive unit housing (34) includes two parallel and vertical housing flanges (41, 42). One housing flange (41) is attached to a frame flange (211), and another housing flange (42) is attached to another frame flange (212), each defining a flange pair. Each of the two flange pairs includes at least one rubber support (80). The frame flanges (211, 212) are connected to their respective housing flanges (41, 42) in a floating and rubber-elastic manner via the at least one rubber support. This ensures that the housing flanges (41, 42) do not directly abut against their respective frame flanges (211, 212), but are spaced apart from them by an axial gap (58) with a gap dimension X of at least 0.3 mm. The rubber support (80) includes a generally annular or cylindrical rubber sleeve (82), wherein the rubber sleeve (82) is disposed in a generally cylindrical annular gap (100) between a rigid outer sleeve (90) and a rigid inner sleeve (70).

2. The electric bicycle drive unit fixing structure (50) according to claim 1, wherein, The outer sleeve (90) is located in the through hole (49) of the housing flange (41, 42).

3. The electric bicycle drive unit fixing structure (50) according to claim 1 or 2, wherein, The inner sleeve (70) is directly and rigidly attached to the frame flange (211, 212) by means of force locking and / or shape locking.

4. The electric bicycle drive unit fixing structure (50) according to claim 3, wherein, The inner sleeve (70) includes an internal thread (76), and the external thread (56) of a bolt (52) inserted from the distal end into the stepped through hole (27) of the frame flange (211, 212) is screwed into the internal thread (76).

5. The electric bicycle drive unit fixing structure (50) according to claim 1, wherein, The rubber sleeve (82) includes a limiting ring (88) arranged axially between the outer sleeve (90) and the corresponding frame flanges (211, 212).

6. The electric bicycle drive unit fixing structure (50) according to claim 1, wherein, A shape-locking structure is provided on the inner side of the outer sleeve (90) and the outer side of the inner sleeve (70), and the shape-locking structure is shape-lockedly engaged with the complementary shape-locking structure on the outer and inner sides of the rubber sleeve (82).

7. The electric bicycle drive unit fixing structure (50) according to claim 1, wherein, The outer casing (90) includes an anti-rotation structure (98) at its proximal longitudinal end, and the outer casing (90) is supported in an anti-rotation manner on the drive unit housing (34) by the anti-rotation structure (98).

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